Abstract：
The diffraction limit is one of the main obstacles in the development of microscopes to analyze the morphology and structure of materials. The main idea of near field scanning optical microscopy (NSOM) is to overcome the diffraction limit using sub-wavelength apertures. In this work, the near-field is simulated in the vicinity of three-dimensional nano-optical apertureless probes. For this purpose, the Helmholtz equation is solved using the boundary element method (BEM). The effects of different parameters on the near field generated in the vicinity of the optical probe are studied. These parameters consist of the length and radius of the probe, the size of the aperture, the angle of the tapered tip, and the geometry of the probe tip. The main advantages of the proposed method are the high accuracy, the very short calculation time, and the ability to calculate the near field inside and outside the optical probe without any approximation.
摘要：
衍射极限是发展显微镜分析材料形貌和结构的主要障碍之一。近场扫描光学显微镜（NSOM）的主要思想是使用亚波长孔径克服衍射极限。在这项工作中,在三维纳米光学无孔探针附近模拟了近场。为此,使用边界元法(BEM)求解Helmholtz方程。研究了不同参数对光学探头附近产生的近场的影响。这些参数包括探头的长度和半径，光圈的大小，锥形尖端的角度，和探针尖端的几何形状。该方法的主要优点是精度高,非常短的计算时间，以及在没有任何近似的情况下计算光学探头内外的近场的能力。
